1. Field of the Invention
The present invention relates generally to hearing prostheses, and more particularly, to recording and retrieval of sound data in a hearing prosthesis.
2. Related Art
Hearing loss, which may be due to many different causes, is generally of two types, conductive and sensorineural. In some cases, a person may have hearing loss of both types. Conductive hearing loss occurs when the normal mechanical pathways to provide sound to hair cells in the cochlea are impeded, for example, by damage to the ossicles. Conductive hearing loss is often addressed with conventional auditory prostheses commonly referred to as hearing aids, which amplify sound so that acoustic information can reach the cochlea.
In many people who are profoundly deaf, however, the reason for their deafness is sensorineural hearing loss. This type of hearing loss is due to the absence or destruction of the hair cells in the cochlea which transduce acoustic signals into nerve impulses. Those suffering from sensorineural hearing loss are thus unable to derive suitable benefit from conventional hearing aids due to the damage to or absence of the mechanism that naturally generates nerve impulses from sound. As a result, hearing prostheses have been developed to provide persons with sensorineural hearing loss with the ability to perceive sound.
Hearing prostheses include but are not limited to hearing aids, auditory brain stimulators, and Cochlear™ prostheses (commonly referred to as Cochlear™ prosthetic devices, Cochlear™ implants, Cochlear™ devices, and the like; simply cochlea implants herein.) Cochlear implants use direct electrical stimulation of auditory nerve cells to bypass absent or defective hair cells that normally transduce acoustic vibrations into neural activity. Such devices generally use an electrode array inserted into the scala tympani of the cochlea so that the electrodes may differentially activate auditory neurons that normally encode differential pitches of sound. Auditory brain stimulators are used to treat a smaller number of recipients with bilateral degeneration of the auditory nerve. For such recipients, the auditory brain stimulator provides stimulation of the cochlear nucleus in the brainstem.
Cochlear implants typically comprise external and implanted or internal components that cooperate with each other to provide sound sensations to a recipient. The external component traditionally includes a microphone that detects sounds, such as speech and environmental sounds, a speech processor that selects and converts certain detected sounds, particularly speech, into a coded signal, a power source such as a battery and an external transmitter antenna.
The coded signal output by the speech processor is transmitted transcutaneously to an implanted receiver/stimulator unit, commonly located within a recess of the temporal bone of the recipient. This transcutaneous transmission occurs via the external transmitter antenna which is positioned to communicate with an implanted receiver antenna disposed within the receiver/stimulator unit. This communication transmits the coded sound signal while also providing power to the implanted receiver/stimulator unit. Conventionally, this link has been in the form of a radio frequency (RF) link, although other communication and power links have been proposed and implemented with varying degrees of success.
The implanted receiver/stimulator unit also includes a stimulator that processes the coded signal and outputs an electrical stimulation signal to an intra-cochlea electrode assembly. The electrode assembly typically has a plurality of electrodes that apply electrical stimulation to the auditory nerve to produce a hearing sensation corresponding to the original detected sound. Because the cochlea is tonotopically mapped, that is, partitioned into regions each responsive to stimulation signals in a particular frequency range, each electrode of the implantable electrode array delivers a stimulating signal to a particular region of the cochlea.
In the conversion of sound to electrical stimulation, frequencies are allocated to stimulation channels that provide stimulation current to electrodes that lie in positions in the cochlea at or immediately adjacent to the region of the cochlear that would naturally be stimulated in normal hearing. This enables the prosthetic hearing implant to bypass the hair cells in the cochlea to directly deliver electrical stimulation to auditory nerve fibers, thereby allowing the brain to perceive hearing sensations resembling natural hearing sensations.
While developments in signal processing continue to improve the capability of conventional cochlear implant systems to augment or provide an approximate sense of hearing for profoundly deaf persons, it has been found that conventional systems are inherently limited in their ability to fully restore normal hearing. It is desired to improve upon existing arrangements to enable recipients to better perceive and/or understand sounds of interest.